Known ceiling mount intrusion detectors use a PIR sensor. However, one of the biggest challenges with known ceiling mount intrusion detectors is uncertainty in a mount height, which depends on a height of a ceiling in a region in which a ceiling mount intrusion detector is installed.
Many ceiling mount intrusion detectors claim to operate within a mount height range so as to be used in a plurality of different environments. Nevertheless, if the detector is not properly adjusted upon installation, then good performance at all mount heights within a claimed mount height range cannot be guaranteed. Furthermore, it is known that one mount height within the claimed mount range produces the best performance of the detector and that performance declines as the mount height moves away from the one mount height.
For example, some known ceiling mount intrusion detectors claim to operate within the mount height range of 2.4 m-3.3 m or 3.65 m-4.8 m. For the detector with the mount height range of 2.4 m-3.3 m, it is known that the mount height within the mount height range that produces the best performance of the detector is 2.7 m and that performance declines as the mount height moves away from 2.7 m and towards either 2.4 m or 3.3 m. Similarly, for detectors with the mount height range of 3.65 m-4.8 m, it is known that the mount height within the mount height range that produces the best performance of the detector is 4.2 m and that the performance declines as the mount height moves away from 4.2 m and towards either 3.65 m or 4.8 m. In a worst case scenario, the performance will decline to a point where the detector will not identify an alarm condition. Furthermore, neither of the above-identified detectors covers the mount height range of 3.3 m-3.65 m so the performance of the detector mounted within such a range cannot be guaranteed.
In order to guarantee the performance within the mount height range, known ceiling mount intrusion detectors include a mechanism to adjust the mount height of the detector by adjusting a PIR optical system of the detector. However, all known ceiling mount intrusion detectors that include the mechanism to adjust the mount height of the detector include a Fresnel lens and not a mirror. Nevertheless, mirrors provide several advantages as compared to Fresnel lenses. Therefore, it would be desirable for a ceiling mount intrusion detector to include the mirror as well as the mechanism to adjust the mount height.